Die casting machine and casting process



Oct. 31, 1961 w. M. GOLDHAMER 3,006,043

on: CASTING MACHINE AND CASTING PROCESS Filed April 9, 1959 5Sheets-Sheet 1 RAGE RESERVOIR INVENTOR PUMP BY 25mm A" on frs WALTER M.GOLDHAMER Oct. 31, 1961 w. M. GOLDHAMER DIE CASTING MACHINE AND CASTINGPROCESS 5 Sheets-Sheet 2 Filed April 9, 1959 nnl l Nu I I I II IHHHHHHHH u NHI llllllllllHU INVENTOR WALTER M. GOLDHAMER r ATTORNEYSOct. 31, 1961 w. M. GOLDHAMER DIE CASTING MACHINE AND CASTING PROCESS 5Sheets-Sheet 3 Filed April 9, 1959 INVENTOR WALTER M. GOLDHAMER SM nal TATTORN 1961 w. M. GOLDHAMER 3,006,043

DIE CASTING MACHINE AND CASTING PROCESS Filed April 9, 1959 5Sheets-Sheet 4 FlG.-7

7 3 FIG. 8

INVENTOR WALTER M. GOLDHAMER Y 7 w. any; 2 16a ATTORNEYS Oct. 31, 1961w. M. GOLDHAMER DIE CASTING MACHINE AND CASTING PROCESS 5 Sheets$heet 5Filed April 9, 1959 INVENTOR WALTER M. GOLDHAMER Pumd4 luuwb, 111

ATTORNEY Baum M 7' 3,006,043 DIE CASTING MA CHHNE AND QASTKNG PRUQEEESWalter M. G-oidhamer, hairer Heights, Shin, assignor to gig CastingResearch Foundation, Inc., New York,

Filed Apr. 9, 1959, Ser. No. 8953MB 19 Claims. (Cl. 22-4?) Thisinvention relates to die casting operations and apparatus therefor, andhas for its object the provision of an improved die casting machine ofthe type in which the die cavity is either vented to the atmosphere oroperated under reduced pressure prior to and during the injection ofmolten metal. The invention provides means for removing the gas from thedie cavity or mold, including the small amount of residual gas which isconcentrated or compressed by the advancing metal forced into the diecavity.

The invention provides an improved process for forming die castings ingas impervious molds which are provided with a vent or vacuum duct forgas, and means for forcing molten metal into the die cavity, whichcomprises removing the gas from the die cavity through the vent or ductin advance of the metal entering the die cavity, cooling the vent orduct to a temperature below the die cavity and, after filling the diecavity, flowing metal into and freezing it in the vent r duct, therebyefiectively removing the gas from the die cavity.

In die casting, the presence of entrapped gas such as air in the diecavity restrains the flow of the metal into the die cavity causingdefects in the contour of the casting, blow holes or porosity. When theinjection pressure exceeds, for example, one thousand pounds per squareinch, the entrapped gas is compressed and dispersed into the casting.Many proposals have been made and devices have been used to remove thegas from the die cavity by venting to the atmosphere or by theapplication of vacuum but these have not been entirely satisfactorybecause of the inability heretofore to remove the residual gas from thedie cavity in a practical and economical manner.

The invention provides a passageway in the die casting apparatusconnecting the die cavity with a vent to the atmosphere or to a vacuumsystem for evacuating the die cavity while the metal is entering the diecavity and, after filling it, entering the passageway, and means forfreezing the metal in the passageway after all the gas has been removedfrom the die cavity, thereby entirely filling the die cavity withoutobjectionable flow of metal through the passageway. The passagewayconnecting the die cavity to the vent or vacuum system is provided withcooling means to solidify the metal therein and serve as a chill plug toprevent the flow of metal from the die cavity after removal of all thegas.

The die casting apparatus comprises complementary die members which,during casting, are connected together to form, as near as ispractically possible, a gastight cavity for the die casting, and, aftercasting, separated to remove the casting, at least one of the membersbeing movable into engagement with and away from the other die member,means for injecting molten metal into the die cavity, a metal-coolingmember attached to each die member, a continuous passageway formedbetween the die members and the metal cooling members which connects thedie cavity to a vent or a vacuum source. The cooling members arepreferably thermally insulated from the die members to suppress the flowof heat into the cooling members. The passageway consists of two parts,one part between the die members which is at a relatively hightemperature and is larger than the other part of the passageway which isbetween the cooling Patented Get. 31, 1961 members, thereby providing asingle passageway operated at two different rates of metal flow and twodifferent temperatures. This assures that the metal will flow readilyand freely into the die cavity and fill it completely and accuratelybefore the casting solidifies, yet permitting the gas to be vented andthe metal to solidify in the part of the passageway within the coolingmembers and prevent its escape or passage into the vacuum system. Bycarrying the first portion of the incoming casting metal through and outof the die cavity at a rapid rate a more homogeneous and uniformtemperature of the metal of the casting is obtained.

In an effective embodiment of apparatus the die members, preferably ofconventional construction, are rigidly and securely connected to andthermally insulated from the cooling members which include chill blocksin heat exchange contact with a coolant medium and between which thepassageway is formed for the rapid solidification of the metal. Thecooling members are preferably each connected to a die member and one ismovable with the movable die member. The passageway portion between thechill blocks is preferably of serpentine or undulating form to provide alarge cooling area in a small space, and is proportioned incross-sectional area to efiect a rapid removal of gas without anexcessive loss of metal. The frozen metal in the passageway seals oifthe vent or vacuum line, thereby eliminating mechanically operatedvalves, plungers and like means for this purpose. The part of thepassageway between the chill blocks may vary from 0.020 to 0.050 inch inthickness, and the part between the die members is thicker up to, say,about A; inch in thickness. The dimensioning of the passageway isimportant to effect a rapid removal of the gas and also a rapidsolidifying of the metal in the passageway.

The apparatus of the invention makes it possible to remove in one piecethe casting and the connected metal which solidified in the passageway,thereby clearing the passageway for the next cycle at the time ofremoving the casting.

In another aspect of the invention a second passageway as aforementionedis provided for connection to a pressure measuring or recording deviceto permit continuous measurement of the die cavity pressure throughoutthe casting cycle. This passageway is preferably connected to theopposite side of the die cavity from the aforementioned passageway whichvents the cavity. This arrangement enables one to register or to recordsimultaneously both the die cavity vacuum level and the pressure, whichmay also be recorded, in the cylinder which drives the metal injectionpiston. This eliminates the possibility of the instruments merelymeasuring the vacuum level in the vacuum system without regard to therestrictions imposed by the passages into the die cavity.

One of the diflicult problems in vacuum die casting is the rapidevacuation of the die cavity and the rapid injection of the metal. Dueto unavoidable re-entrant air from leaks around the die members, pins,and the like, as well as the residual gas which becomes appreciable asthe metal compresses it, it is important not only to remove this gas butalso to record the amount of its pressure.

These and other novel features of the invention will be betterunderstood after considering the following discussion taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a side elevational view of a conventional die casting machinein horizontal arrangement embodying the invention;

FIG. 2 is a plan view of the cooling members in connection with diemembers of the machine of FIG. 1, in closed position;

FIG. 3 is a side elevational view of FIG. 2;

3 7 FIG. 4 is a sectional enlargement of the lower part of FIG. 2;

FIG. 5 is an enlarged sectional view at 5-5 of FIG. 2;

FIG. 6 is a perspective view of the two cooling members of FIGS. 1 to 5;

FIG. 7 is a sectional side view of a portion of the apparatus of FIG. 1for injecting the molten metal into the die cavity, shown at thebeginning of the injection stroke;

FIG. 8 is a view similar to FIG. 7 at the end of the injection stroke;

FIG. 9 is a view similar to FIG. 7 when one die member has been openedfor removal of the casting;

FIGS. 10 and 11 are cross sections at 10l0 of FIG.

'7 showing the two positions of the injection piston; and

FIG. 12 is a vertical front view taken facing one of the die members ofa modification.

The apparatus illustrated in the drawings and partic ularly as shown inFIG. 1 comprises a die casting machine having a base 1, upright framemembers 2 and 3,

tie bars 4 and 5 interconnecting the frame members, a

.die member 6 securely connected to member 3 which has amatingcomplementary die member 7. The bars 4 and 5 are cross-connected by acarriage 8 which is slidable thereon and to which the die member 7 isconnected by bracket 12. Carriage 8 is connected by linkage 13 to rod 14which is operated by a piston in the cylinder 15 to open and close thedie member 7.

The die members 6 and 7 are machined to effect tight engagement and havea die cavity 16 therebetween which connects by an upright inlet 17leading to the cylinder 18 for the injection of molten metal. Forconvenience of illustration only one die cavity is shown, but it is tobe understood that two or'more interconnected cavities may be used inthe die members. The cylinder 13 is connected to a pipe 26 which isimmersed in the molten metal, for example, aluminum alloys in reservoir21.

'The assembly of apparatus 22 for injecting the molten metal into thedie cavity will be described hereinafter.

The die members 6 and 7 each carry a securely attached cooling member 24and 25 respectively. Between the die members and chill blocks acontinuous vent or evacuation passageway is provided consisting of part26 between the die members which is relatively thick varying from A to Vinch, and part 27 between the cooling members which is relatively thinvarying'from 0.020 to 0.050 inch in thickness based upon the cavityvolume to be evacuated. The pipe 28 as shown connects the passagewaythrough restricting orifice 30, solenoid valve 31 to the vacuumreservoir 32. 7 When the apparatus is not used for vacuum casting, thepipe 28 is eliminated and the passage 27 vents directly to theatmosphere. The valve 31 is connected by line 33 to an electric switch34 on the die members 6 and 7 so that the valve 31 is closed when diemember'7 is open and is opened to apply vacuum to passageway 27 when thedie member 7 is closed. The

orifice is a limiting means to restrict the vacuum at the initial stage.(The valve 31, line 33 and switch 34 may be omitted if desired.)Solenoid valve 35 by-passes valve 31 by pipe 36 and is connected byelectric line 37 to the electrically-operated timer control T. Theoperation of the valves and switches will be described hereinafter.Cooling members 24 and 25 are connected by bolts B to the die members 6and 7 and are accordingly in rigid secured attachment thereto so thatthe cooling member 24 remains in stationary fixed position with diemember 6 and cooling member 25 is moved to the open and closed positionswith die member 7. With particular reference to FIG. 5 it will be notedthat the cooling members engage the die members on narrow projections orlands 40 which provide air spaces 41 between the members to serve asthermal insulation and suppress the flow of heat from the die membersinto the cooling members. The cooling members are each formed of twomain parts, nest blocks 42 and 43 formed of a metal such as stainlesssteel or refractory sintered metal compour ds or other low heatconducting material. In the mating face of block 43 a U-shaped groove44- is provided for the insertion therein of a gas-sealing gasket 45,such as neoprene, silicone, or Teflon. Each of the nest blocks has ahollow center within which is inserted chill blocks 46 and 47. Thesechill blocks have a series of channels C on their back surfaces for thecirculation therein of coolant fluid passed into the channels throughpipes P and discharged from the channels through pipes P. The chillplugs are preferably formed of metal of high heat conductivity such asmolybdenum or copper. The chill plugs have corrugated surfaces 48 and 49which when the chill blocks are in assembled position as shown in FIG. 5form the tortuous passageway 27a as a part of passageway 27. Thisundulating passageway extends from the recess in the lower end of achill block 46 to a chamber 5%? formed in the nest block 25 as shown inFIG. 5. The nest block 42 has a projecting baffle 52 extend- .ing intothe space 56 and also a space 53 contiguous with .der to facilitate theremoval of the metal that solidifies in the passageway 27 the edges 55of the corrugations are beveled. As shown in FIGS. 4 and 6, an ejectorpin 56 having a projecting head 57 may be inserted in an opening throughthe nest block and the chill block and has an exterior extension whichstrikes the frame of the machine when the mold is opened. When the diemember 7 and its cooling member 25 are opened the injector head 57strikes against the metal in the passageway 27 and effects its removal.

If it is desired to measure or record the pressure in the die cavity,additional chill blocks 38' and 39 are connected to the die members 6and 7, respectively, to provide a passageway 39' connected to the diecavity 16 as is the passage 26 and 27. This passageway is connected to apressure measuring device 29 which may be a gage or a recording pressuremeasuring device to register or record the pressure in the die cavityduring casting.

This passageway is connected to the die cavity at a place remote fromthe passageway 26 and permits measuring the actual pressure in the diecavity 16. An alternative arrangement is shown in FIG. 12.

7 The apparatus 22 shown in detail in FIGS. 7-11 is for the controlledinjection of measured quantities of molten metal'into the die cavity 16.This apparatus comprises a cylinder 18 secured to the die member 6 whichopens into the duct 17 leading directly into the die cavity 16.

extends forward only to the point 62, the functions of which will bedescribed hereinafter. The rod 59 which drives the piston 58 has a head64 in secured but rotatable connection with the sleeve 65. This sleevealso efiects a threaded connection with the piston rod 66 of the pistonoperated in the cylinder 67. A locking nut 68 secures the sleeve to bothhead 64' and rod 66. The cylinder 67 is mounted on a frame 69 and isrigidly attached to the upright frame 3 by two tie rods 72 and 73. Therod 66 is sealed where it passes through the frame 69 with a stufiinggland 74. The piston operable in cylinder 67 is not shown but isunderstood to be an hydraulically operated piston for driving rods 66,59 and the piston 58 in response to the cyclic control means'for themachine.

The head 64 has a transverse slot 63 in which the lever arm 75 isinserted. This lever arm has a slot 76 in which ton 58. As best shown inFIG. 10, a bracket 78 is secured to the rod 72. This bracket supports acylinder 80 having therein an hydraulically operated piston (not shown)which moves the rod 81 and its attached pin 77 backward and forward toturn the lever 75. It will be noted with reference to FIGS. 7 and 8 thatthe bracket 78 is stationary and remains in secured attachment to therod 72. The lever 75 engages the pin 77 only when the piston 58 is atthe rearward end of its stroke as shown in FIG. 7. The piston incylinder 80 is operated hydraulically by fluid admitted thereto by thesolenoid valve 82. This valve is actuated by the timer T of the castingmachine through an electrical circuit connected with line 83. The pistonof cylinder 80 is advanced at the end of each machine cycle to turnpiston 58 to the position shown in FIGS. 7 and 10, and is retracted atthe end of the low level evacuation of the die cavity to turn the piston58 to the position shown in FIGS. 8 and 11.

The piston in cylinder 15 and the piston in cylinder 67 are operatedhydraulically by valve means controlled from the timer T of the castingmachine.

The casting apparatus of the invention is operated as follows: When thecentral timer T is set for operation, the piston in cylinder 15 forcesthe carriage 8 and the die member 7 with its attached cooling member 25to the closed position shown in FIGS. 1, 5, 7 and 8. At this time theswitch 34 is closed and the valve 31 is open causing a limited vacuum,due to the orifice 30, to be created in the passageways 26 and 27, diecavity 16, duct 17 and cylinder 18. At this time, the lever 75 hasturned the piston 58 to the position shown in FIGS. 7 and and a chargeof molten metal is sucked upwardly through pipe 20 from the reservoir 21into the cylinder 18. A short interval thereafter based on the volume ofthe metal required, the timer T operates sequentially the piston incylinder 80, the solenoid valve 35 and the piston in cylinder 67. Thepiston in cylinder $0 turns the lever 75 from the position shown in FIG.10 to the position shown in FIG. 11 thereby completely disconnecting theforward portion of cylinder 18 from pipe 20. This movement sets thegroove 61 over the passage in pipe 20, connecting it to the atmospherecausing the molten metal in contact with piston 58 to return immediatelyto the vessel 21, thereby preventing this metal from freezing in contactwith the piston. At the conclusion of the setting of piston 58, thesolenoid valve 35 is opened to apply full vacuum and then the piston incylinder 67 forces the rods 66 and 59 and piston 58 forward on theinjection stroke and the metal in cylinder 18 is forced through thepassage 17 and upwardly into the die cavity 16. During this motion andwhile the full vacuum is applied the metal is entering and filling diecavity 16 and ultimately passes upwardly and with considerable rapiditythrough the relatively large passageway part 26 and then into therelatively narrow passageway part 27' which is within the coolingmembers 24 and 25. As a result of the conjoint action of the advancingmetal and the vacuum all of the gases contained in the die cavity areremoved. A low vacuum as generally used in this are will remove most ofthe gas from the die cavity. However, when a small amount of residualgas, mostly infiltrated air, is concentrated by the advancing metal, itbecomes a contaminant for the metal and results in casting defects andrejects. My improved apparatus removes this residual gas by forcing itinto the vacuum system and then freezing the metal in the vent to serveas a plug.

Any small particles of solid metal that may have been retained in thepassageways 26 and 27 are blown against the bafile 52 and are trapped bythe fibrous metal 54 and thereby prevented from entering the vacuumsystem. As a result of the low temperature of the chill blocks 46 and 47the metal in the passageway part 27 is completely solidified before itreaches the chamber 50.

At the completion of this operation the casting machine timer T closesvalve 35, reverses the piston in cylinder 15 to move the carriage 8 andthe attached die member 7 and cooling member 25 towards the left asviewed in FIG. 1 to open the mold and permit removal of the die casting.Coincident with this movement the ejector part 55 strikes a lug (notshown) on the machine frame and the extreme end 57 thereof which entersthe passageway 27 engages an edge portion of the metal web therein andkicks it loose. As a consequence the entire mass of solidified metal andthe metal web of the passageway is removed in a single piece.

FIG. 12 illustrates a modification of the apparatus of FIG. 1 and is aside view at the inner face of the die member 7 showing the mounting ofthe cooling member 25 and a second cooling member 25. This coolingmember has a complementary cooling member (not shown) similar to member24 on die member 6, which forms the passageway 2'7 to which the gage orrecording device 29 is attached. It will be noted that the passage 26'enters the cavity 16 at a position opposite the outlet passage 26. Thispermits the pressure in the die cavity to be measured independently ofthe pressure in the vacuum system and especially in passageway 26.

My copending application Serial No. 818,079, filed June 4, 1959,describes and claims more fully the improved piston for injecting themolten metal, and also a vertical ram piston as used in zinc diecasting. This invention is also applicable to such zinc die castingapparatus in which the piston or ram operates in a pot of molten metal.

This application is a continuation-in-part of my copending applicationSerial No. 675,206, filed June 30, 1957, now abandonded.

I claim:

1. In a die casting machine including complementary die members whichcan be connected together to form a die cavity and separated to removethe casting, at least one of the die members being movable intoengagement with and away from the other die member, means for injectingmolten metal under pressure into the die cavity, a separate metalcooling member secured to each die member, thermal insulating meansdisposed between the die members and the metal cooling members forsuppressing the flow of heat from the die members into the metal coolingmembers, at least one of said metal cooling members being movable intoengagement with and away from the other metal cooling member duringmovement of the die member to which it is secured, means defining apassageway between the engaged metal cooling members connected to avaccum duct and to the die cavity, and means for cooling the metalcooling members to solidify metal in said passageway before the metalsolidifies in the die cavity.

2. A die casting machine as defined in claim 1 which comprises a diemember and a metal cooling member connected together and movable as aunit to open and close both the die cavity and the passagewaysimultaneously whereby the casting and the attached metal from thepassageway may be removed as a unit.

3. A die casting machine as defined in claim 1 which comprises metalcooling members each having a chill block which engages the other chillblock and between which the passageway is formed, said chill blocksbeing formed of a metal of high heat conductivity in comparison with themetal of the mold and having means for the circulation thereon of acoolant liquid.

4. A die casting machine as defined in claim 1 in which the passagewaybetween the chill blocks varies from 0.020 to 0.050 inch and isundulating to provide a long travel for the metal in a short space.

5. A die casting machine as defined in claim 1 which comprises airspaces between the die members and the metal cooling members as thermalinsulation to suppress the flow of heat from the die members into thecooling members. i

6. In a die casting machine including complementary :die members whichcan be connected together to'form a die cavity and separated to removethe casting, at least one of the die members being movable intoengagement with and away from the other die member, means for inectingmolten metal under pressure into the die cavity, a separate metalcooling member secured to each die member, thermal insulating meansdisposed between the die members and the metal cooling members forsuppressing the flow of heat from the die members into the metal coolingmembers, at least one of said metal cooling members being movable intoengagement with and away from the other metal cooling member duringmovement of the die member to which it is secured, means defining apassageway between the engaged metal cooling members connected to avacuum duct and to the die cavity, a passageway between the die membersconnected to the passageway between the cooling members, the passagewaypart between the cooling members being at least 0.020 inch thick andtortuous for the rapid solidification of metal therein, the passagewaypart between the die members being much thicker for the rapid flow ofmetal therein from the die cavity, and means for cooling the metalcooling members.

7. A die casting machine as defined in claim 6 which compriseselectrical switch means operated with the movable die member and anelectrically operated valve in the vacuum duct for evacuating thepassageway and die cavity when the die member is in closed position.

8. A die casting machine as defined in claim 7 which comprises a secondelectrically operated valve in the vacuum duct for efiecting an initialvacuum in the die cavity which is followed by a lower vacuum when thefirst-mentioned electrically operated valve is opened.

9. In a die casting machine of the type having a die cavity and meansfor injecting molten metal therein under pressure, the improvement whichcomprises one die member having a part of the die cavity therein whichis immovably secured to the machine, a cooling member fixed to the diemember, thermal insulating means disposed between the die members andthe metal cooling members for suppressing the flow of heat from the diemember into the cooling member, a complementary die member also having apart of the die cavity therein, another cooling member fixed to thecomplementary die member, thermal insulating means disposed between thedie members and the metal cooling members for suppressing the flow ofheat from the complementary die member into the cooling member attachedthereto, means for circulating a cooling fluid in the cooling members,means for moving the complementary die member and its cooling memberfixed thereto into close fitting contact with the die member and itscooling member respectively, means between the die members and thecooling members defining a passageway which passageway is connected atone part to a source of vacuum and at another part to the die cavity,said passageway between the cooling members is tortuous and the partformed between the die members is not tortuous whereby the metal, afterfilling the die cavity, enters the passageway forming residual gas notremoved by the vacuum out ahead of it and then enters the tortuous partand solidifies in the passageway part between the cooling members, andmeans for moving the complementary die member and its cooling memberaway from the fixed die member and its cooling member for the removal ofthe die casting and the metal solidified in the passageway as a unitarystructure.

10. In a die casting machine including complementary die memberscooperating to provide a die cavity, one of said members being movableto open and close said cavity, a metal inlet communicating with saidcavity in one of said members, a bi-sectional separable heat exchangeron said members having an air outlet passageway not less than 0.020 inchin thickness therein communicating with said cavity, a vacuum lineconnected to said passageway, means for passing a cooling fluid incontact with the heat exchangers, a molten metal reservoir adjacent oneof said die members, a cylinder superjaceut thereto communicating withsaid cavity, a piston in said cylinder, a conduit in said reservoirconnected to said cylinder, a valve in said vacuum line, a by-pass linehaving a restricted passageway therein which is looped around saidvalve, a second valve in said by-pass line, electric means operated bysaid piston for actuating the first named valve, and a second electricmeans operated by one of said die members for actuating the second namedvalve.

11. In a die casting machine including complementary die memberscooperating to provide a die cavity, one of said members being movableto open and close said cavity, a metal inlet communicating with saidcavity in one of said members, a separable bi-sectional heat exchangeron said members having an air outlet passageway not less than 0.020 inchin thickness therein when closed communicating with said cavity, meansfor passing a cooling fluid in contact with said heat exchangers, avacuum line connected to said passageway, a metal reservoir adjacent oneof said die members, a metal injecting piston cylinder assemblycommunicating with the reservoir, valve means in said vacuum lineoperable by said movable die member for the closure of the vacuum linewhen the die members are separated but which is opened when the diemembers are closed, a second valve in the vacuum line which by-passesthe first-mentioned valve, and a timer for operating both the secondvalve and the injection piston, said timer operating the second valve insequence after the operation of said piston.

12. In a die casting machine including complementary die memberscooperating to provide a die cavity, one of said members being movableto open and close said cavity, a metal inlet communicating with saidcavity in one of said members, a separable bi-sectional heat exchangeron said members having a passageway therein when closed communicatingwith said cavity, means for passing a cooling fluid in contact with saidheat exchangers, a first vacuum line connected to said passageway, asecond vacuum line having a restriction therein communicating with thefirst named vacuum line, a

metal reservoir adjacent one of said die members, a cylindercommunicating with said reservoir and said metal inlet to said cavity,valve means in said first vacuum line to control the application ofvacuum, and a second valve means in said second vacuum line to vary theamount of the vacuum.

13. A die casting machine comprising a fixed die member and aconfronting reciprocal die member having a mold cavity therein, one ofsaid die members having a metal inlet passageway therein communicatingwith said mold cavity, a metal outlet passageway for the mold cavityformedibetween the die members which varies in thickness from A to incha separable heat exchanger embodying separable sections mountedrespectively on each die member, said sections forming a space in themating faces thereof constituting a molten metal passageway not lessthan 0.020 inch in thickness when said sections are closed whichconnects to the metal outlet passageway, each section of said heatexchanger having channels therein adjacent said passageway between thecooling members for the circulation of a coolant liquid to solidifymolten metal therein after the mold cavity is filled, said heatexchanger embodying an external jacket formed of a material of lowerheat conductivity than said die members, thermal insulating meansdisposed between each heat exchanger and its die member to suppress theflow of heat from the die member to the heat exchanger, and an internalbody formed of a material of high heat conductivity, whereby the moltenmetal will flow through said heat exchanger and be chilled thereinbefore it solidifies in said die cavity.

14. A die casting machine comprising a fixed die member and aconfronting reciprocal die member having a mold cavity therein, one ofsaid die members having a metal inlet passageway therein communicatingwith said mold cavity, a heat exchanger embodying divided separablecooling members having an exterior portion formed of a metal of lowerheat conductivity than said die members, and an interior portion of amaterial of higher heat conductivity than said die members, each coolingmember thereof being attached to each die memher, the interior portionof said cooling member having a Wave-like molten metal outlet passagewaynot less than 0.020 inch in thickness when the cooling members areclosed with said die members, means in said heat exchanger for rapidlyremoving from said passageway heat to reduce the temperature thereofbelow the temperature of said die members, the engaging areas of saidcooling members with said die members being insulated by air gaps tosuppress the fiow of heat from the die members into the cooling members.

15. In a die casting machine including complementary die members havingrecesses in the mating faces thereof defining a die cavity, one of saiddie members being movable towards and away from the other die member toopen and close said cavity, means for injecting molten metal underpressure into the die cavity, a separate metal cooling member secured toeach die member, means for suppressing the flow of heat from the diemembers into the metal cooling members, at least one of said metalcooling members being movable into engagement with and away from theother metal cooling member during movement of the die member to which itis secured, a passageway between the engaged metal cooling membersconnected to a vacuum duct and to the die cavity, and means for coolingthe metal cooling members to solidify metal in said passageway beforethe metal solidifies in the die cavity, separate means on each diemember forming therebetween a second passageway connected to the diecavity, one of said means being movable with the movable die member,said second passageway also extending between metal cooling members, andmeans connected to the second passageway to measure the pressure in thedie cavity during the filling of the die cavity with metal.

16. A die casting machine as defined in claim 15 in which the separatemeans are each a metal cooling member maintained at a lower temperaturethan the die members.

17. The improved process for forming die castings by the high-pressureinjection of metal into gas-impervious hot molds having die cavitiesprovided with passage means for the removal of gas from and the forcingof molten metal into the die cavities of the molds and in which a partof the passage means for the removal of gas is tortuous and formedbetween cooling members which are insulated from the molds, whichcomprises removing gas from the die cavities through the passage meansin advance of the molten metal being forced into the die cavities,cooling the tortuous part of the passage means to a temperature belowthe temperature of the die cavities by the circulation of a coolingfluid in heat exchange contact with the cooling members, after fillingthe die cavities forcing metal into the tortuous passage means andfreezing the metal therein to form a plug and stop the further flow ofmolten metal from the die cavities.

18. In the process of claim 17, maintaining a vacuum in the passagewayto evacuate the die cavity as the die cavity is being filled.

19. In the process of claim 17, measuring the pressure in the die cavitythrough a separate passageway.

References Cited in the file of this patent UNITED STATES PATENTS1,606,236 Kadow Nov. 9, 1926 2,210,544 Galloway Aug. 6, 1940 2,243,835Brunner et al. June 3, 1941 2,248,868 Hanawalt July 8, 1941 2,371,604Brennan Mar. 20, 1945 2,610,372 Schraeder Sept. 16, 1952 2,785,448Hodler Mar. 19, 1957 2,786,234 Beyer Mar. 26, 1957 FOREIGN PATENTS302,974 Switzerland Ian. 17, 1955 UNITED STATES PATENTOFFICE CERTIFICATEOF CORRECTION Patent No 3 OO6 O43 0ctobegygl 1961 Walter M Goldhamer dthaterror appears in the above numbered pat- It is hereby certifie aidLetters Patent should read as ent requiring correction and that the scorrected below.

Column 7 line 58 for "forming". read forcing *1,

Signed and sealed this 3rd day of April 1962.,

(SEAL) Attest:

ERNEST W. SWIDRR Attesting Officer DAVID L. LADD Commissioner of Patents

